This is how my mind works as I'm always buying cheap MX5s, tinkering and moving them on at no profit
It's like all 'classic cars' If its in fantastic condition you can try to find a collector of older cars. Who may pay £3k to £4k.
If it's averagely worn then get it 12 months MOT and sell it to someone willing to take a punt on a summer fun car, say up to £1500 or settle for half that.
You might have got a less vague answer if you had posted a picture of it showing its worst/best features and Reg No so people could check MOT history.
Good luck